The present invention relates to seals, and particularly to metal face seals.
The present invention has particular application to the earthmoving and heavy equipment vehicle field, wherein seals are operated in highly destructive or abrasive environments. The invention has particular application to use of wheels on large off-road vehicles such as trucks.
The type of environment thus described creates seal problems and has resulted in some solutions. For example, Hasselbacher et al, U.S. Pat. No. 3,524,654, shows a prior art metal to metal face seal especially suited to such environments, and which has received a certain degree of success. Another example is Durham et al, U.S. Pat. No. 3,403,916, showing a multiple seal arrangement of a metal to metal type. Both of these examples show metal to metal face seals which are retained by elastomeric torics and are contained between inclined ramps of retainer structures. These seals are especially suited to application to crawler tractors and the bearings thereof, wherein vehicle speeds and seal ring diameters are relatively small compared with those encountered on truck vehicles. As the seal diameter increases, the surface velocity at the seal face increases, thus increasing heat and centrifugal force problems. In addition, the seals tend to tilt from the plane perpendicular to the rotational axis, thus resulting in instability.
One solution to some of these problems is shown in Maguire et al, U.S. Pat. No. 3,905,607, wherein a single seal ring is employed for sealing against a relatively movable seal ring. The single seal ring is biased by means of the toric. However, this arrangement is not entirely satisfactory in view of the fact that the arrangement thus described is not pressure balanced.